Abstract: Angle data ranging from 0° to 360° obtained by performing polar conversion with respect to a periodic signal are input to a low pass filter having: a phase accumulator for outputting smoothed angle data; a phase comparator for obtaining a phase error between the angle data and the smoothed angle data; a first amplifier for amplifying the phase error; a second amplifier for further amplifying the phase error; an integrator for integrating the phase error PE amplified by the second amplifier to obtain a velocity error; and an adder for adding the phase error amplified by the first amplifier and the velocity error to determine a control voltage. The phase accumulator controls the frequency of the smoothed angle data so that the phase error is zero based on the control voltage to remove a high frequency component in the angle data.

Abstract: A stable signal is output in which when there is no movement, unstable output change does not occur, and an output change exceeding a predetermined limit does not occur. The variation &Dgr;PH in the output angle signal PH to be output is subjected to hysteresis and through rate limitations with respect to the variation APF in the input angle signal input thereto. When the variation APF in the input signal is in a hysteresis range of −Hys<&Dgr;PF<+Hys, the variation in the output angle signal is output as 0. When the variation &Dgr;PF in the input signal is in a hysteresis range of &Dgr;PF<−(Hys+SR) or &Dgr;PF>(Hys+SR), a through rate limitation is effected to thereby clip the variation in the output angle signal to SR. When the variation &Dgr;PF is in other regions, the output follows the input linearly with the output delayed by the hysteresis quantity.

Abstract: A position detector detects the position of a detector section relative to a record medium having recorded thereon a periodic position signal. The detector section has two detectors that produce first and second detection signals that are polar converted and processed, based on the number of divisions in a quadrant of the periodic position signal.

Abstract: Resin-made support panels for supporting the ischium torus, lumbar and shoulder blade portions of a person seated are molded integral onto sheet-like springs which are plain-woven by resin fibers, and side rims of the sheet-like springs are connected to frames by means of hooks.

Abstract: A seat cushion is disclosed which comprises a rectangularly extending frame having opposed side portions; a flat sheet member arranged within a space defined by the rectangular frame; connecting devices for connecting each side portion of the flat sheet member to one of the opposed side portions of the frame; a plastic panel member having side portions raised, the plastic member being disposed on the flat sheet member leaving between each of the raised side portions and corresponding one of the opposed side portions of the frame a generally wedge-shaped clearance; a cushion structure tightly mounted on the plastic panel in such a manner that side portions of the cushion structure are raised by the raised side portions of the plastic panel; and two cushion pad units respectively received in the wedge-shaped clearances defined below the raised side portions of the plastic panel member.